## Multiple Machines

Cockpit can connect to multiple machines from a single Cockpit session. These are listed in the host switcher.

These additional machines are accessed via SSH from the machine that the first machine connected to, and are authenticated with the logged in user's password and/or SSH keys.

SSH host keys are stored in `/etc/ssh/ssh_known_hosts`.

The machine data is stored in `/etc/cockpit/machines.d/*.json`, or below `$XDG_CONFIG_DIRS` if set (see cockpit.conf). Settings in lexicographically later files amend or override settings in earlier ones. Cockpit itself writes into `99-webui.json`; packages or admins who want to pre-configure machines should ship files like `05-mymachine.json` so that changes from the web interface override the pre-configured files.

Each JSON file contains an object that maps machine IDs to objects that define the properties of that machine. The ID can be a human readable name or an IP address or any other unique value, and is shown in the web interface until conneting to it the first time, at which point the web interface will show the machine's host name.

The following properties are recognized:

`"address"` | (string, mandatory) IP address or DNS name of the machine
`"visible"` | (boolean, optional) If `true`, the machine will be displayed and available for managing with Cockpit. If `false` (the default), it will not be displayed, but still taken into account for type-ahead search when adding new machines in the web interface.
`"user"` | (string, optional) User name on the remote machine. When not given, Cockpit will default to the user name that was being used to log into Cockpit itself.
`"port"` | (integer, optional) ssh port of the remote machine. When not given, the default port 22 is used.
`"color"` | (string, optional) Color to assign to the machine label in the web interface. This can be either given as `rgb(r_value, g_value, b_value)` with each value being an integer between 0 and 255, or as a color name like `yellow`. When not given, Cockpit will assign an unused color automatically.

Example:

    {
        "web server": {
            "address": "192.168.2.4",
            "visible": true,
            "color": "rgb(100, 200, 0)",
            "user": "admin"
        },
        "192.168.2.1": {
            "address": "192.168.2.1",
            "port": 2222,
            "visible": true,
            "color": "green"
        }
    }